With the advent of EPA automotive fuel mileage ratings, HR6831 "The National Energy Act", Public Law 94-163 mandating minimum fuel economy standards for automobiles, and increasing costs, it becomes both logical and desirable to accommodate the vehicle operator with an instrument that indicates vehicle fuel economy. To accomplish the requirements of indicating fuel mileage economy, such as vehicle average miles per gallon, sufficiently accurate with a compact arrangement of components, a computing mechanism for solving miles per gallon equal miles divided by gallon is required. Such a mechanism constitutes the subject of this patent application which is a continuation-in-part of my co-pending U.S. application for a vehicle energy conservation indicating device and process for use, Ser. No. 861,965 filed on Dec. 19, 1977 now, U.S. Pat. No. 4,186,296 which also disclosed certain embodiments of such a computing mechanism. More than any other product of technology the road vehicle is the focus or unresolved conflict arising from the limited energy resources. The average vehicle consumes its own weight in fuel each year, about 700 gallons, totaling over 28 percent of the petroleum consumption in the United States Fuel economy is a complex function or many factors such as (1) power plant performance including accessories, (2) aerodynamic drag, (3) tire resistance, (4) inertial mass, (5) driving pattern and habits, and (6) length or trip and environmental conditions including ambient temperature, humidity, wind direction and force, terrain (level or hilly). Of these six categories of factors the vehicle operator has it within his power to control and/or influence all factors excluding environmental and original vehicle design characteristics. Vehicle maintenance and operator driving habits are two of the most important factors influencing fuel economy.
By way of illustration it is interesting to note that a 20 percent decline in fuel economy on a typical vehicle rated at 20 miles per gallon and consuming 700 gallons of fuel per year at rated mileage economy, would result in a loss of 175 gallons of fuel at a cost of $105, using $0.60 per gallon fuel in March 1978 which has increased 100 percent to $1.20 per gallon in March 1980. Simple mathematics based on $0.60 per gallon fuel and 100 million vehicles gives an estimated total of $17.5 billion gallons, valued at some $10.5 wasted in one year. This is the equivalent of a train or tank cars approximately 20,714 miles long.
Another important consideration in vehicle fuel economy is keeping the operator informed of the actual day to day fuel economy being experienced with each specific vehicle-operator combination. The key link between vehicle performance and energy conservation is the vehicle operator. In order to conserve energy the operator must be aware of his vehicle fuel economy performance relative to rated fuel economy. It is obvious, therefore, that to achieve meaningful economy and conservation on a continuing basis a need exists for the improved vehicle fuel economy and energy conservation indicating device of the present invention.